Electric system and method for energizing the electric system

ABSTRACT

An electric system is disclosed. The electric system comprises a battery subassembly, a current limiter, a non-current-limiting path in parallel with the current limiter, a battery management system (BMS) adapted for causing the battery assembly to energize the electric system using the current limiter upon a start of a precharge phase, and an electric vehicle module (EVM) communicatively coupled to the BMS. The EVM is adapted for causing the battery assembly to energize the electric system using the non-current-limiting path following a completion of the precharge phase. The electric system may be integrated in an electric vehicle. A method for energizing an electric system is also disclosed.

CROSS-REFERENCE

The present application is a division of United States Pat. ApplicationNo. 17/233,628, filed on Apr. 19, 2021, which is a division of UnitedStates Pat. Application No. 16/464,676, filed on May 28, 2019, nowUnited States Pat. No. 10,992,164, issued on Apr. 7, 2021, which is aNational Phase Entry of International Patent Application No.PCT/IB2017/057544, filed on Nov. 30, 2017, which claims priority toUnited States Provisional Pat. Application No. 62/428,281, filed on Nov.30, 2016, the entirety of all of which is incorporated herein byreference.

FIELD OF TECHNOLOGY

The present technology relates to rechargeable battery systems for usein vehicles.

BACKGROUND

Electric vehicles, including hybrid vehicles, use secondary batteriessuch as for example lithium-ion batteries to power electric motors forpropulsion. These vehicles also carry 12V lead-acid auxiliary batteriesto provide standby power, system wake-up, software updates and start ofan internal combustion engine (ICE) when present.

FIG. 1 is a simplified circuit diagram of a prior electric vehicle. Acircuit 100 comprises a battery pack 102 that includes four (4) modulegroups 104, 106, 108 and 110 connected in series. An example of such abattery pack and module groups is described in International PatentPublication Number WO 2016/120857 A1 to Lebreux et al, published on Aug.4, 2016, the disclosure of which is incorporated by reference herein inits entirety. In this example, each module group 104, 106, 108 and 110comprises a plurality of battery cells (not shown) that each can provideelectric power at 24 volts. Overall, the battery pack 102 is capable ofproviding electric power at 96 volts.

According to the SAE Surface Vehicle Standard J1673 MAR2012, vehiclesystems that contain a circuit operating above 50 volts (DC) areconsidered “high voltage” and surpass a higher limit of a low voltagerange. Similar technical standards and/or regulations exist for otherregions, such as the European Union’s Directive 2006/95/EC whichpertains to circuits over 75 volts (DC) and the United Nations’ UNECER100 for vehicles of category M&N or UNECE R136 for vehicles of categoryL which pertains to circuits over 60 volts (DC). To this end, a serviceswitch 112, located between the module groups 106 and 108, is normallyclosed to ensure continuity between the module groups 104, 106, 108 and110. When maintenance needs to be performed on the vehicle, the serviceswitch 112 may be opened manually by maintenance personnel. By openingthe service switch 112, no point of the circuit 100 can ever be at avoltage exceeding that of two (2) module groups, for example 48V on FIG.1 , this voltage being defined by the combination of the module groups104 and 106 or by the combination of the module groups 108 and 110.

When energized by the battery pack 102, a DC-DC converter 114 convertsthe 96V power down to 12V for charging a 12V lead-acid battery 116. Inturn, the lead-acid battery 116 powers a vehicle control module (VCM)118. When the vehicle is started by the user, for example using a startkey (not shown) to close a starting switch 120, the VCM 118 energizes arelay coil 122. Activation of the relay coil 122 causes the closing ofpower switches 124 and 126 to cause energizing of a motor control module(MCM) 128 by the battery pack 102. The MCM 128 converts the 96V electricpower from the battery pack into three-phase AC current for powering anelectric motor 130. Fuses 132 and 134 are provided to protect thecircuit 100 in case of fault. Variants of the circuit 100 may differ butgenerally operate in similar manners.

While lead-acid batteries are relatively inexpensive, they are heavy,have poor energy density, and occupy considerable volume within thevehicles. Considering these factors, integration of lead-acid batteriesconsiderable cost to vehicles as a whole.

Because several key components of electric vehicles need 12V supply forproper operation, including for system start-up, lead-acid batteries arestill present in today’s electric vehicles. Some of the reasons for thecontinued use of regular 12V lead-acid batteries include the importantdevelopment effort and cost that would be necessitated for validatingmany vehicle functionalities that currently rely on current 12Vlead-acid batteries if used with 12V lithium-ion batteries. Some vehiclemanufacturers contend that the lower cost of ownership and weightreduction that could be obtained by the substitution of lead-acidbatteries with lithium-ion batteries would not compensate such cost andeffort.

Lead-acid batteries lose their charge over time; this is particularlyproblematic in the case of vehicles used for recreational purposesbecause they may be used quite infrequently. Over discharge of auxiliarylead-acid batteries is a frequent cause of failure of current electricvehicles. One manner of preserving the charge of the lead-acid battery116 requires moving the starting switch 120 to another position (notshown) in the circuit 100 so that a continuous connection is maintainedbetween the battery pack 102 and the DC-DC converter 114. With suchconfiguration, the DC-DC converter 114 maintains the lead-acid battery116 charged as long as the battery pack 102 holds a charge. However,when the vehicle remains unused for an extended period of time, a slowdischarge of the lead-acid battery 116 may lead to a complete dischargeof the battery pack 102. This could be the case for example when arecreational vehicle adapted for use in the summer is not used for thewhole winter. Minimizing current leakage at the system level isparticularly important in the context of recreational vehicles.

Therefore, there is a desire for battery systems that compensate forproblems related to the use of lead-acid batteries in electric vehicles.

SUMMARY

It is an object of the present technology to ameliorate at least some ofthe inconveniences present in the prior art. Systems and methoddisclosed herein are applicable, in particular but not exclusively, foruse in rechargeable electric vehicles such as motorcycles,all-terrain-vehicles, snowmobiles, personal watercraft and the like.

The present technology provides an electric system useful for poweringan electric vehicle. The electric system may include modern rechargeablebattery assembly while not requiring the use of a traditional auxiliarylead-acid battery. The battery assembly includes two batterysubassemblies that can provide high-voltage power to an electric motorwhen connected in series. The two battery subassemblies are separablewhen the electric system is not in use and not connected to a charger.An interrupter connects a first battery subassembly to a second batterysubassembly. The interrupter closes in two (2) phases when powering orcharging the electric system. Initially, upon start of a prechargephase, the interrupter places a current-limiting path between the twobattery subassemblies in order to form a current-limited battery source.Thereafter, following a completion of the precharge phase, theinterrupter places a non-current-limiting path between the two batterysubassemblies in order to form a non-current-limited battery source. Inan aspect, the first battery subassembly initiates the establishment ofthe current-limiting path between the two battery subassemblies tothereby allow powering of a system controller. Thereafter, the systemcontroller initiates the establishment of the non-current-limiting pathbetween the two battery subassemblies.

According to a first aspect of the present technology, there is providedan electric system comprising a first battery subassembly; a secondbattery subassembly; an interrupter adapted for connecting the first andsecond battery subassemblies in series, the interrupter comprising aswitched current-limiting path in parallel with a switchednon-current-limiting path; and a system controller electricallyconnected to the first battery subassembly and to the second batterysubassembly; and the first battery subassembly being adapted for causingclosing of the switched current-limiting path when an energizing triggeris applied to the electric system; and the system controller beingadapted for causing closing of the switched non-current-limiting pathwhen energized by the first and second battery subassemblies.

In some implementations of the present technology, the system furthercomprises a first contactor of the switched current-limiting path and afirst coil, the first battery subassembly being adapted for energizingthe first coil for closing the first contactor and the switchedcurrent-limiting path; and a second contactor of the switchednon-current-limiting path and a second coil, the system controller beingadapted for energizing the second coil for closing the second contactorand the switched non-current-limiting path.

In some implementations of the present technology, the interrupterfurther comprises a service switch.

In some implementations of the present technology, the current-limitingpath comprises a resistor adapted for limiting a current flowing betweenthe first and second battery subassemblies and having a power ratingadapted for dissipating an energy caused by the current flowing throughthe resistor.

In some implementations of the present technology, the first batterysubassembly comprises a first battery module connected in series to asecond battery module; and the second battery subassembly comprises athird battery module connected in series to a fourth battery module.

In some implementations of the present technology, the first batterymodule comprises a first battery management system (BMS) operativelyconnected to an activation switch, the energizing trigger being appliedto the activation switch.

In some implementations of the present technology, the second batterymodule comprises a second BMS; the third battery module comprises athird BMS; and the fourth battery module comprises a fourth BMS.

In some implementations of the present technology, the first BMS isadapted for cascading the energizing trigger to the second BMS; thesecond BMS is adapted for cascading the energizing trigger to the thirdBMS; the third BMS is adapted for cascading the energizing trigger tothe fourth BMS; and at least one of the first, second, third and fourthBMSs is communicatively coupled to the system controller and is adaptedfor informing the system controller of the energizing trigger.

In some implementations of the present technology, the at least one ofthe first, second, third and fourth BMSs is adapted for detecting anabnormal condition and for informing the system controller of theabnormal condition.

In some implementations of the present technology, the at least one ofthe first, second, third and fourth BMSs is adapted for recording a logof the abnormal condition.

In some implementations of the present technology, the system controlleris adapted for detecting an abnormal condition and for informing the atleast one of the first, second, third and fourth BMSs of In someimplementations of the present technology, the system controller isadapted for recording a log of the abnormal condition.

In some implementations of the present technology, the abnormalcondition is selected from an abnormal voltage of one or more of thefirst, second, third and fourth battery modules, an abnormal temperatureof one or more of the first, second, third and fourth battery modules,an abnormal temperature of a motor powered by the electric system, anexcessive level of current flowing through one or more of the first,second, third and fourth battery modules, detection of a user activationof an emergency stop switch, and detection of a user activation of ahazard switch,

In some implementations of the present technology, the electric systemis adapted for opening the switched non-current-limiting path toshutdown the electric system when the abnormal condition is a severeabnormal condition.

In some implementations of the present technology, a maximum operatingvoltage of each of the first and second battery subassembliesindividually is less than a high voltage limit; and when the switchednon-current-limiting path is closed, a combined voltage of the first andsecond battery subassemblies is greater than the high voltage limit.

In some implementations of the present technology, the high voltagelimit is 60 Volts.

In some implementations of the present technology, a combined voltage ofthe first and second battery subassemblies is 96 volts.

In some implementations of the present technology, the first and secondbattery subassemblies provide a nominal system voltage when connected inseries.

In some implementations of the present technology, the system furthercomprises a voltage converter adapted for converting the nominal systemvoltage to a control voltage, the nominal system voltage being greaterthan the control voltage; the system controller being adapted for beingenergized with the control voltage.

In some implementations of the present technology, the system furthercomprises a motor; and a motor controller adapted for being energizedwith the control voltage and for delivering electric power from thefirst and second battery subassemblies to the motor at the nominalsystem voltage.

In some implementations of the present technology, the motor is an ACmotor; the motor controller is an AC motor controller further comprisingan inverter adapted for converting the nominal system voltage into an ACvoltage and for delivering electric power from the first and secondbattery subassemblies to the AC motor at the AC voltage.

In some implementations of the present technology, the AC motor is amulti-phase motor; and the inverter is adapted for delivering electricpower from the first and second battery subassemblies to the multi-phasemotor at a multi-phase AC voltage.

In some implementations of the present technology, the motor is adaptedfor delivering electric power to the motor controller when a brakingforce is applied to the motor; and the motor controller is adapted fordelivering electric power to the first and second battery subassemblieswhen the braking force is applied to the motor.

In some implementations of the present technology, the system controlleris adapted for closing the switched non-current-limiting path when acondition is met, the condition being selected from at least one of aminimum time delay having been spent after the closing of the switchedcurrent-limiting path, a voltage sensed on a load-side of the electricsystem having reached a minimum voltage threshold, and a current flowingthrough the first and second battery subassemblies having fallen below amaximum current threshold.

In some implementations of the present technology, the system furthercomprises a start button operatively connected to the first batterysubassembly, the start button being adapted for providing the energizingtrigger for starting the electric system.

In some implementations of the present technology, the system furthercomprises a charger switch operatively connected to the first batterysubassembly, the charger switch being adapted for providing theenergizing trigger and for delivering electric power for charging thefirst and second battery subassemblies.

In some implementations of the present technology, the system controlleris adapted for signaling to the first battery subassembly when theswitched non-current-limiting path is closed, and the first batterysubassembly is adapted for opening the switched current-limiting path inresponse to receiving the signaling.

In some implementations of the present technology, the system controlleris adapted for opening the switched non-current-limiting path toshutdown the electric system.

According to a second aspect of the present technology, there isprovided a vehicle comprising an electric system comprising a firstbattery subassembly; a second battery subassembly; an interrupteradapted for connecting the first and second battery subassemblies inseries, the interrupter comprising a switched current-limiting path inparallel with a switched non-current-limiting path; and a systemcontroller electrically connected to the first battery subassembly andto the second battery subassembly; and the first battery subassemblybeing adapted for causing closing of the switched current-limiting pathwhen an energizing trigger is applied to the electric system; and thesystem controller being adapted for causing closing of the switchednon-current-limiting path when energized by the first and second batterysubassemblies, the vehicle being an electric or hybrid vehicle.

According to a third aspect of the present technology, there is provideda method for energizing an electric system. The method comprisesapplying an energizing trigger to a first battery subassembly; inresponse to the energizing trigger, connecting the first batterysubassembly in series to a second battery subassembly via acurrent-limiting path; delivering electric power from the first andsecond battery subassemblies to energize a system controller; and oncethe system controller is energized, connecting the first batterysubassembly in series to the second battery subassembly via anon-current-limiting path.

In some implementations of the present technology, the first and secondbattery subassemblies provide a nominal system voltage when connected inseries.

In some implementations of the present technology, the method furthercomprises converting the nominal system voltage to a control voltage,the nominal system voltage being greater than the control voltage; andenergizing the system controller with the control voltage.

In some implementations of the present technology, the electric systemcomprises a motor and a motor controller, the method further comprisingenergizing the motor controller with the control voltage; and deliveringelectric power from the motor controller to the motor at the nominalsystem voltage.

In some implementations of the present technology, the motor is an ACmotor and a motor controller, the method further comprising energizingthe motor controller with the control voltage; converting the nominalsystem voltage into an AC voltage; and delivering electric power fromthe motor controller to the AC motor at the AC voltage.

In some implementations of the present technology, the AC motor is amulti-phase motor; and the electric power is delivered to themulti-phase motor at a multi-phase AC voltage.

In some implementations of the present technology, the first batterysubassembly comprises a first battery module connected in series to asecond battery module; and the second battery subassembly comprises athird battery module connected in series to a fourth battery module.

In some implementations of the present technology, the energizingtrigger is applied to the first battery module, the method furthercomprising successively cascading the energizing trigger from the firstbattery module to the second, third and fourth battery modules.

In some implementations of the present technology, connecting the firstbattery subassembly to the second battery subassembly is controlled bythe first battery module.

In some implementations of the present technology, the current-limitingpath is in parallel with the non-current-limiting path, the methodfurther comprising closing a service switch in series with thecurrent-limiting and non-current-limiting paths.

In some implementations of the present technology, the energizingtrigger is a start command; the first battery subassembly or the secondbattery subassembly forwards an indication of the start command to thesystem controller; and the system controller controls an operation ofthe electric system in response to the indication of the start command.

In some implementations of the present technology, the start command isa transient command.

In some implementations of the present technology, the energizingtrigger is a charging command; the first battery subassembly or thesecond battery subassembly forwards an indication of the chargingcommand to the system controller; and the system controller controlscharging of the first and second battery subassemblies in response tothe indication of the charging command.

In some implementations of the present technology, the charging commandis a continuous command.

In some implementations of the present technology, connecting the firstbattery subassembly in series to the second battery subassembly via thenon-current-limiting path is delayed until a condition is met, thecondition being selected from at least one of a minimum time delayhaving been spent after connecting the first and second batterysubassemblies via the current-limiting path, a voltage provided by thefirst and second battery subassemblies having reached a minimum voltagethreshold, and a current flowing through the first and second batterysubassemblies having fallen below a maximum current threshold.

In some implementations of the present technology, the method furthercomprises disconnecting the current-limiting path between the first andsecond battery subassemblies after connecting the first and secondbattery subassemblies via the non-current-limiting path.

In some implementations of the present technology, the method furthercomprises opening the non-current-limiting path to shutdown the electricsystem.

According to a fourth aspect of the present technology, there isprovided an electric system, comprising a battery assembly; a currentlimiter; and a first battery management system (BMS) adapted for causingthe battery assembly to energize the electric system using the currentlimiter upon a start of a precharge phase and for causing the batteryassembly to energize the electric system without the current limiterfollowing a completion of the precharge phase.

According to a fifth aspect of the present technology, there is provideda method of energizing an electric system. The method comprises applyingan energizing trigger to the electric system; in response to theenergizing trigger, energizing the electric system from acurrent-limited battery source during a precharge phase; and followingcompletion of the precharge phase, energizing the electric system from anon-current-limited battery source.

According to a sixth aspect of the present technology, there is providedan electric system comprising a first battery module comprising at leastone first battery cell, a first battery management system (BMS) and afirst BMS switching power supply, the at least one first battery celland the first BMS switching power supply being disconnected when thefirst BMS is in an inactive state, the at least one first battery celland the first BMS switching power supply being connected when the firstBMS is in a powered state; a second battery module electricallyconnectable to the first battery module, the second battery modulecomprising at least one second battery cell, a second BMS and a secondBMS switching power supply, the at least one second battery cell and thesecond BMS switching power supply being disconnected when the secondbattery module is in an inactive state, the at least one second batterycell and the second BMS switching power supply being connected when thesecond BMS is in a powered state; and a user-controlled switch adaptedfor causing a connection of the at least one first battery cell to thefirst BMS switching power supply for energizing the first BMS and forchanging the first BMS from the inactive state to the powered state; thefirst BMS being adapted for causing a connection of the at least onesecond battery cell to the second BMS switching power supply forenergizing the second BMS and for changing the second BMS from theinactive state to the powered state when the first BMS is in the poweredstate; the first BMS being further adapted for closing acurrent-limiting path placed in series between the first and secondbattery modules to start a precharge phase of the electric system once acommunication between the first BMS and the second BMS is established.

In some implementations of the present technology, the first BMS isfurther adapted for performing initial verifications before closing thecurrent-limiting path.

In some implementations of the present technology, the initialverifications comprise a confirmation of the communication between thefirst BMS and the second BMS.

Additional and/or alternative features, aspects and advantages ofimplementations of the present technology will become apparent from thefollowing description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a simplified circuit diagram of a prior electric vehicle;

FIG. 2 is a block diagram of an electric system including batterymodules according to an implementation;

FIG. 3 is a partial view of the electric system of FIG. 2 , showinginternal details of a battery module;

FIG. 4 is another partial view of the electric system of FIG. 2 , in animplementation having an AC motor control module (MCM) and an AC motor;

FIG. 5 is a finite state diagram of a battery management system (BMS);

FIG. 6 is a finite state diagram of an electric vehicle module (EVM);and

FIG. 7 is a logic diagram for a method for energizing the electricsystem of FIG. 2 according to an implementation.

DETAILED DESCRIPTION

The present technology describes an electric system and a method forenergizing an electric system. The electric system and the method may beintegrated in a rechargeable electric vehicle having an electric motor.The electric system and the method may also be integrated in arechargeable hybrid vehicle that includes an electric motor and aninternal combustion engine.

Referring now to the drawings, FIG. 2 is a block diagram of an electricsystem 200 including battery modules 202, 204, 206 and 208 according toan implementation. The electric system 200 comprises a battery assemblythat includes two (2) battery subassemblies 282 and 284. One batterysubassembly 282 further comprises the battery module 202 connected inseries to the battery module 204. The battery module 202 is a “leader”module and the battery module 204 is a “follower” module. Anotherbattery subassembly 284 further comprises the battery module 206connected in series to the battery module 208, the battery modules 206,208 being further follower modules. The battery module 202 is the leadermodule in that it is the first of these four (4) battery modules 202,204, 206, 208 on which an energizing trigger is applied upon start ofthe electric system 200 or upon charging of the electric system 200, toinitiate a precharge phase of the battery assembly. Although four (4)battery modules 202, 204, 206, 208 are represented on FIG. 2 ,implementations of the electric system 200 comprising as few as two (2)battery modules are contemplated. Other contemplated implementations mayinclude many more battery modules and there is no a priori limitation tothe number of battery modules that may be part of the electric system200.

Each battery module 202, 204, 206, 208 includes a battery controller, orbattery management system (BMS) 210, 212, 214 and 216 respectively. Thevarious BMSs 210, 212, 214 and 216 may be identical or may be distinctdepending on the respective features of the battery modules 202, 204,206, 208. In an implementation, the BMSs 210, 212, 214 and 216 maycomprise a processor (not shown) having executable code for controllingthe features of the battery modules 202, 204, 206, 208. It iscontemplated that not every battery module 202, 204, 206, 208 beprovided with its own BMS, i.e. that the functions of the BMSs 210, 212,214 and 216 could be combined into three (3) or fewer BMSs housed withinthree (3) or fewer of the battery modules 202, 204, 206, 208, or indeedoutside the battery modules 202, 204, 206, 208. It is also contemplatedthat the functions of the BMSs 210, 212, 214 and 216 be divided intomore than four (4) BMSs located within or outside the battery modules202, 204, 206, 208.

Each battery module 202, 204, 206, 208 comprises a number of batterycells 222 connected in a series and/or a parallel arrangement forproviding a rated voltage, for example 24 volts, between their positiveterminals 224 and their negative terminals 226. The positive terminal224 ₁ of the first battery module 202 is connected to the negativeterminal 226 ₂ of the second battery module 204 so that a maximumoperating voltage of the first battery subassembly 282 between thenegative terminal 226 ₁ of the first battery module 202 and the positiveterminal 224 ₂ of the second battery module 204 is of 48 volts.Likewise, the positive terminal 224 ₃ of the third battery module 206 isconnected to the negative terminal 226 ₄ of the fourth battery module208 so that a maximum operating voltage of the second batterysubassembly 284 between the negative terminal 226 ₃ of the secondbattery module 206 and the positive terminal 224 ₄ of the fourth batterymodule 208 is of 48 volts. When connected in series in the mannerdescribed hereinbelow, all four (4) battery modules 202, 204, 206 and208 provide a nominal system voltage of 96 volts on a load side of theelectric system 200, between DC leads 278 and 280. Implementations inwhich another nominal system voltage is provided by connecting differentbattery modules, or by connecting a different numbers of batterymodules, are also contemplated. In various implementations, the nominalsystem voltage obtained when connecting the two battery subassemblies282, 284 in series exceeds a standard high voltage limit, for example 60volts, while the maximum operating voltage of each battery subassembly282, 284 is less than this high voltage limit when isolated from oneanother.

The first and second battery subassemblies 282, 284 are connected to aninterrupter 228. The interrupter 228 includes a switchedcurrent-limiting path 286 including a contactor 230 and a resistor 232.The interrupter 228 also includes a switched non-current-limiting path288 including a contactor 234. The switched current-limiting path 286 isconnected in parallel to the switched non-current-limiting path 288,both of these paths 286, 288 being connected in series to a normallyclosed service switch 236 and to a system fuse 238. The service switch236 may be placed in an open position for servicing of the electricsystem 200, so that no voltage exceeding the high voltage limit ispresent in the electric system 200. The system fuse 238 protects theelectric system 200 against current overloads.

Other techniques may be contemplated for implementing the switchedcurrent-limiting and non-current limiting paths 286, 288 of theinterrupter 228. In non-limiting examples, the resistor 232 may besubstituted with an inductance (not shown) alone or in combination witha power transistor (not shown) and a solid-state relay (not shown), apower transistor (not shown) may be gradually turned on using pulsewidth modulation while taking advantage of an intrinsic inductance ofthe electric system 200.

In an implementation comprising a large number of battery modules, thesebattery modules may be grouped into several battery subassemblies, eachbattery subassembly including one or more battery modules, an additionalinterrupter such as the interrupter 228 being inserted between each pairof battery subassemblies.

The switched current-limiting path 286 forms a current limiter for thebattery assembly. When the contactor 230 is closed, upon start of aprecharge phase, the battery subassemblies 282, 284 and the switchedcurrent-limiting path 286 form a current-limited battery source. Whenthe contactor 234, the battery subassemblies 282, 284 and the switchednon-current-limiting path 288 form a non-current-limited battery source.Of course, the contactor 234, the service switch 236, the system fuse238 and connections therebetween may all offer a low, yet measurableresistance. Likewise, the battery modules 202, 204, 206, 208 may eachhave their own output impedance and may thus not be able to provide thesystem voltage at an infinite current level. In the context of thepresent disclosure, the expression “non-current-limiting path” and“non-current-limited battery source” will be understood as relativeterms in view of the expressions “current-limiting path” and“current-limited battery source”.

The various BMSs 210, 212, 214, 216 are communicatively coupled via aconnection 218. The connection 218 may extend serially between thesuccessive battery modules 202 to 208 or may alternatively provide astar connection from the leader module to the follower modules. The BMS210 of the first battery module 202 uses the connection 218 to informthe other BMSs 212, 214, 216 of the energizing trigger that causes thestart of the precharge phase.

The energizing trigger may be applied to the BMS 210 by auser-controlled switch, in two (2) distinct situations. Oneuser-controlled switch is a start button 240 connected to the BMS 210.Another user-controlled switch is a contactor 246 of a charger 242, thecontactor 246 also being connected to the BMS 210. The charger 242includes a plug 244 for connecting to an external power source, forexample to a 110 volts AC outlet or to a 220 volts AC outlet (notshown). The contactor 246 closes when the charger 242 is connected tothe external power source. The energizing trigger may be applied to theBMS 210 in the form of a transient start command when a user of theelectric system 200 depresses the start button 242. The energizingtrigger may alternatively be applied to the BMS 210 in the form of acontinuous charging command, or latched command, when the contactor 246is closed.

In an implementation, the energizing trigger is applied in the form of adry contact closure of the start button 240 or of the contactor 246,this action closing an electric path allowing energy from battery cellscontained in the battery module 202 to feed and wake-up the BMS 210.FIG. 3 is a partial view of the electric system of FIG. 2 , showinginternal details of a battery module. In an implementation, the batterymodules 202, 204, 206, 208 are all constructed in the manner as shown onFIG. 3 . In particular, FIG. 3 shows the battery module 202 and itsconnection to the start button 240. The BMS 210 comprises a switchingpower supply 650, a processor 652, and a communication interface 250.The switching power supply 650 is disconnected from the battery cells222, and therefore inert, when the BMS 210 is in an inactive state. Whenthe start button 240 or the contactor 246 is closed, providing theenergizing trigger, an internal contact 654 of the switching powersupply 650 closes and allows the switching power supply 650 to connectto the battery cells 222. The switching power supply 650 thus becomesenergized by the battery cells 222. Although the internal contact 654may open again, if the energizing trigger is released, internal controllogic of the switching power supply 650 allows the BMS 210 to remain ina powered state by maintaining a contact with the battery cells 222. Theswitching power supply 650 energizes the communication interface 250 andthe processor 652. Once energized, the processor 652 performsinitialization operations that are described hereinbelow. The processor652 energizes an internal coil 656 to cause closing of an internalcontact 658 electrically connected to the connection 218. This action ofthe BMS 210 emulates the dry contact closure of the start button 240 orof the contactor 246 and effectively causes, within the BMS 212, aclosure of a corresponding internal contact, such as the contact 654,for activating the BMS 212. By this action, the energizing trigger iscascaded from the BMS 210 to the BMSs 212, 214 and 216. More broadly,closure of the internal contact 658 establishes a communication betweenthe BMSs 210, 212, 214 and 216 over the connection 218.

In an implementation, the first battery module 202 includes anactivation switch 220 on which the above-mentioned energizing trigger isapplied. The activation switch 220 may either be a physical switchdistinct from the BMS 210 or may instead be integrated within the BMS210. Other contemplated techniques for implementing the energizingtrigger include the detection of a current flowing between theactivation switch 220 and the start button 240 or the contactor 246, orthe provision of digital signaling information from the start button 240or from the contactor 246 to the activation switch 220. In the same oranother implementation, the energizing trigger may be applied to theactivation switch 220 by an electronic device (not shown) replacing thestart button 240 and the contactor 246, the electronic device includinga small battery (not shown), for example a lithium-ion watch battery.

A format of information transmitted on the connection 218 from the BMS210 to the BMSs 212, 214, 216 about the energizing trigger may differfrom a format of the energizing trigger as received by the BMS 210. Inan implementation, the connection 218 is an electrical connectionbetween the BMSs 210, 212, 214, 216 and the BMS 210 emulates the closureof a dry contact so that the BMSs 212, 214, 216 may wake up in the samemanner as illustrated in the foregoing description of FIG. 3 . Inanother implementation, the information transmitted on the connection218 may be realized as a digital signal.

Resulting from the application of the energizing trigger on the BMS 210of the first battery module 202, the BMS 210 energizes a coil 248operatively connected to the first contactor 230. The first contactor230 closes, effectively closing the switched current-limiting path 286so that the two battery subassemblies 282, 284 become connected inseries via the current limiter that includes the resistor 232 forprecharging the electric system 200. The resistor 232 limits a currentflowing through the battery modules 202, 204, 206, 208 during theprecharge phase. The resistor 232 has a current-limiting value and apower rating that are adapted for dissipating energy created in theresistor 232 by the current flowing therethrough. This current istransient in nature and rapidly reduces as the voltage between thepositive terminal 224 ₄ of the fourth battery module 208 and thenegative terminal 226 ₁ of the first battery module 202 is reaching the96V nominal system voltage while charging capacitances (not shown) ofelements of the electric system 200. As a result, a voltage availablebetween the positive terminal 224 ₄ of the fourth battery module 208 andthe negative terminal 226 ₁ of the first battery module 202 rapidlyincreases toward the 96 volts nominal system voltage.

At least one of the battery modules 202, 204, 206, 208 includes thecommunication interface 250 controlled by the respective BMS 210, 212,214, 216 and communicatively coupled to a system controller for theelectric system 200, for example an electric vehicle module (EVM) 252,via a system bus 254. The at least one communication interface 250informs the EVM 252, via the system bus 254, of the energizing trigger.This information forwarded to the EVM 252 is either in the form of anindication of a start command, if the energizing trigger applied to theBMS 210 is a transient start command indicating a start of the electricsystem 200, or in the form of an indication of a charging command, ifthe energizing trigger is a continuous charging command, or latch,indicating that the battery modules 202, 204, 206 and 208 of theelectric system 200 are being recharged. A format of the indicationforwarded on the system bus 254 may differ from a format of theenergizing trigger as applied to the BMS 210. Generally speaking, theforwarded indication may include a binary information element indicatingthe nature of the energizing trigger. Otherwise stated, the indicationdoes not need to be continuously present on the system bus 254 while thebattery modules 202, 204, 206 and 208 of the electric system 200 arebeing recharged.

In the battery modules 202, 204, 206, 208, the communication interface250 may be operatively connected to the corresponding BMS 210, 212, 214,216. Alternatively, the communication interface 250 may form an integralpart of the BMS 210, 212, 214, 216. As all BMSs 210, 212, 214, 216 areinterconnected and because information about the energizing trigger isforwarded from the BMS 210 to the other BMSs 212, 214, 216, any one ofthe battery modules 202, 204, 206, 208 may inform EVM 252 of theenergizing trigger via its communication interface 250 and via thesystem bus 254. In an implementation, the EVM 252 is made aware, via thesystem 254, of proper handling of information about the energizingtrigger by each of the BMSs 212, 214, 216.

In an implementation, the EVM 252 is energized by a voltage converter256, for example a DC/DC converter, that converts the nominal systemvoltage of 96 volts to a control voltage of 12 volts present between DCleads 290 and 292. In a mode of operation, after closing of the firstcontactor 230 to close the switched current-limiting path 286, thevoltage converter 256 rapidly provides the 12 volts control voltage tothe EVM 252. In turn, the EVM 252 energizes a coil 258 that isoperatively connected to the second contactor 234. This action closesthe second contactor 234, in turn closing the switchednon-current-limiting path 288 of the interrupter 228. The two batterysubassemblies 282, 284 including the four (4) battery modules 202, 204,206, 208 are now ready to deliver electric power to the electric system200 without the current limiter, at the 96 volts nominal system voltageand at a current rating of the battery modules 202, 204, 206, 208. Onceenergized, the EVM 252 generally controls the various components of theelectric system 200.

Energizing the coil 258 to close the second contactor 234 may take placeas soon as the EVM 252 is energized. Alternatively, in animplementation, the EVM 252 may wait until it has received informationabout the energizing trigger on the system bus 254 and has performedvarious system verification tasks before triggering the energizing ofthe electric system 200 without the current limiter by energizing thecoil 258. In the same or another implementation, energizing the coil 258may take place after each of the BMSs 210, 212, 214, 216 has informedthe EVM 252 of their successful initialization. In the same or otherimplementations, the EVM 252 may delay energizing of the coil 258 untilone or more of the following conditions is met: a minimum time delayhaving been spent after the closing of the switched current-limitingpath 286 by the closing of the first contactor 230, a voltage sensed ona load-side of the electric system 200, on the DC leads 278, 280,between the positive terminal 224 ₄ of the fourth battery module 208 andthe negative terminal 226 ₁ of the first battery module 202 havingreached a minimum voltage threshold close to the nominal system voltage,or a current flowing through the first and second battery subassemblies282, 284 has fallen below a maximum current threshold.

In an implementation, once in a “run” state, the EVM 252 may signal theBMS 210 of the battery module 202, via the system bus 254, to enter ashutdown sequence. Alternatively, the EVM 252 may receive a signal fromthe BMS 210 and enter the shutdown sequence. The EVM 252 de-energizesthe coil 258 at the end of the shutdown sequence, resulting in theopening of the second contactor 234 and removal of the control voltageon the EVM 252.

In the implementation as shown, the electric system 200 further includesadditional components including a motor control module (MCM) 128 and amotor 130. The MCM 128 is energized by the control voltage suppliedbetween DC leads 294 and 292 for logical operations taking place in theMCM 128 and by the nominal system voltage, via the DC leads 278 and 280,for power delivery to the motor 130. The motor 130 may be a DC motorrated to operate at the nominal system voltage. Alternatively, the motor130 may be an AC motor, for example a three-phase AC motor or amulti-phase AC motor, operating at an AC voltage provided by an inverterof the MCM 128. An example of an inverter is shown in a later Figure.The EVM 252 provides commands to the MCM 128 via a driving bus 260 tocontrol operation of the motor 130, for example for acceleration anddeceleration of the motor 130, based on throttling commands provided bya user and received at the EVM 252. In an implementation, when theenergizing trigger is in the form of a continuous start command,indicating that the charger 242 is connected to the external powersource for recharging the battery modules 202, 204, 206, 208, the EVM252 may refrain from sending, to the MCM 128 via the driving bus 260,any command that could lead to operation of the motor 130.

In an implementation, when the motor 130 is subject to a braking force,it may return electric power to the MCM 128. In turn, the MCM 128converts the received electric power to the nominal system voltageapplied to recharge the battery modules 202, 204, 206, 208. In animplementation where the electric system 200 is integrated in a hybridvehicle, the motor 130 may return electric power to the MCM 128 when aninternal combustion engine (not shown) mechanically drives the motor130.

In the implementation as shown, other components of the electric system200 include an instrument cluster 262 powered by the control voltage onthe DC leads 290, 292 and communicatively coupled with the EVM 252 viathe system bus 254. The instrument cluster 262 may for example displayinformation about a current charge of the battery assembly as well asother useful information such as a current ambient temperature, the timeof day, and the like. A parking brake module (PBM) 264, a vehicleimmobilizer module (VIM) 266 operatively connected to the EVM 252 forproviding authorization to activate the vehicle propulsion and providingan emergency or stop command to the EVM 252, an emergency stop switch268, for example the conventional “red button” on a motorcycle, operableby the user of the electric system 200 for providing an emergency stopcommand to the EVM 252, a hazard switch 270 operable by the user of theelectric system 200 for controlling, via the EVM 252, turning on of aflashing hazard light via a hazard relay coil 272 are also included inthe electric system 200 of FIG. 2 . In an implementation, when thehazard switch 270 has been used to turn on the flashing hazard light, avariant of the shutdown sequence may comprise keeping the coil 258energized so that the EVM 252 remains energized and keeps the hazardrelay coil 272 energized until the hazard switch 270 removes itscommand.

A key switch 274 connected to a vehicle key (not shown) of a vehicleintegrating the electric system 200 is provided to prevent powering theMCM 128 with the control voltage by opening a connection between the DCleads 290 and 294 when the vehicle switch is not present. This vehiclekey may further be connected to the VIM 266 and attached to the user sothat the vehicle will stop should the user fall from the vehicle. TheMCM 128 may regularly send continuity messages, for example heartbeatmessages, to the EVM 252 on the condition that the vehicle key remainsattached to the vehicle. For some applications, a secondary voltageconverter 276 may provide an accessory voltage, in particular, but notexclusively, an accessory voltage higher than the control voltage, forexample 13.5 volts, for powering demanding accessories such as forexample an assisted electric power steering (not shown).

FIG. 4 is another partial view of the electric system of FIG. 2 , in animplementation having an AC motor control module (MCM) 600 and an ACmotor 606. FIG. 4 shows the MCM 600 having an input capacitor 610, aprocessor 602 and an inverter 604 for driving the AC motor 606. Theinput capacitor 610 is initially charged at the nominal system voltageduring the precharge phase. The processor 602 is powered by the voltageconverter 256 at 12 volts on DC leads 294, 292 while the inverter ispowered at 96 volts on the DC leads 278, 280. The processor 602 receivescommands from the EVM 252 via the driving bus 260 to control operationof the motor 606. The processor 602 in turn converts these commands intocontrol signals applied to gates G₁-G₆ of transistors T₁-T₆ of theinverter 604. As shown on FIG. 4 , the inverter 604 also includesfreewheel diodes D₁-D₆ that are used to attenuate transient overvoltagethat occurs upon switching on and off of the transistors T₁-T₆. The ACmotor 606 has three (3) phases A, B and C connected to in a stararrangement to a neutral point 608, each one of the phases A, B and Cbeing connected between corresponding pairs of the transistors T₁-T₆.The 96 volts power from the battery modules 202, 204, 206, 208 isconverted by the inverter 604 into a three-phase AC voltage applied tothe three phases A, C and C of the AC motor 606.

FIG. 5 is a finite state diagram of a battery management system (BMS).In an implementation, a finite state diagram 300 shown on FIG. 5 isapplicable to the BMS 210 of the first battery module 202. In the sameor another implementation, the finite state diagram 300 is alsoapplicable to the BMSs 212, 214 and 216. The diagram 300 illustratesmany possible state variations of the BMS 210. In an implementation, thestates that are illustrated in the diagram 300 are software states ofthe BMS 210. The following description of these states will be bestunderstood considering FIG. 2 and its description.

An initial state of the BMS 210 is an “Off” state 302, when the electricsystem 200 is not operating (i.e. not turned on by the user) and whenthe charger 242 is not connected to the external power source. The BMS210 is not powered in the Off state 302. In this initial state, thebattery modules 202, 204, 206, 208 may be charged, partially charged, ornot charged.

The BMS 210 transits from the Off state 302 to an “Initialization” state304 in a wake-up condition of the electric system 200, when one of thestart button 240 or the contactor 246 applies the energizing trigger tothe BMS 210. Now energized and awake, the BMS 210 executes systemverification tasks while in the Initialization state 304. One of theverifications made by the BMS 210 may comprise a confirmation of acommunication, via the connection 218, to the other BMSs 212, 214 and216. Any failure of the tasks performed by the BMS 210 while in theInitialization state 304 causes the BMS 210 to move to a “Shutdown”state 314, which is described hereinbelow. After completion of the tasksof the Shutdown state 314, the BMS 210 terminates its processingfunctions, cuts a connection between the battery cells 222, and returnsto the Off state 302.

The wake-up condition may be present when the BMS 210 receives, via thesystem bus 254, an indication that the electric system 200 is connectedto a computer or similar device (not shown), in which case the BMS 210transits from the Initialization state 304 to a “Bootloader” state 306for receiving a firmware update, or a calibration update. The BMS 210normally returns to the Off state 302 once the update is completed.

Alternatively the wake-up condition may be present when the energizingtrigger is applied to the BMS 210 in one of the above-described manners,following which the BMS 210 moves to a “Precharge” state 308. In thePrecharge state 308, the BMS 210 energizes the coil 248 to close thecontactor 230 and to thereby close the switched current-limiting path286 of the interrupter 228 for a period of time, generally until aminimum time period has expired or until a current flowing through thebattery modules 202, 204, 206, 208 and through the resistor 232 fallsbelow a predetermined value. Instead of a current measurement, a voltagemeasurement of the battery module 202 or voltage measurements of severalof the battery modules 202, 204, 206, 208 is also contemplated fordetermining when the BMS 210 is ready to move to a next state.Thereafter, the BMS 210 may move from the Precharge state 308 to a“Charging” state 310, if the energizing trigger is a continuous chargingcommand, indicating that the battery modules 202, 204, 206 and 208 ofthe electric system 200 are being recharged. Alternatively, the BMS 210may move to a “Run” state 312, if the energizing trigger is a transientstart command, indicating a start of the electric system 200. In animplementation, a timing for the change of state of the BMS 210 from thePrecharge state 308 to the Charging state 310 or to the Run state 312may be controlled at least in part through a signal received from theEVM 252, via the system bus 254. In the Charging state 310 or in the Runstate 312, the BMS 210 de-energizes the coil 248 to open the contactor230 and thereby open the switched current-limiting path 286 of theinterrupter 228.

If the BMS 210 receives, via the system bus 254, an indication that theelectric system is connected to a source of a firmware update or asource of a calibration update while in the Precharge state 308, the BMS210 may move from the Precharge state 308 to the Bootloader state 306.

Having entered the Charging state 310, the BMS 210 may remain in thatstate for as long as the charger 242 is connected to the external powersource and applies the energizing trigger. Trickle charging of thebattery modules 202, 204, 206, 208 may take place while the BMS 210 isin the Charging state 310. Following a disconnection of the charger 242,the BMS 210 moves to the Shutdown state 314, during which it sends adisconnect indication to the EVM 252 on the system bus 254, and then tothe Off state 302.

Having entered the Run state 312 following a start of the electricsystem 200, the BMS 210 may remain in that state for as long as theelectric system 200 is not stopped by the user or by an abnormalcondition. In a hybrid vehicle implementation where the motor 130 isconfigured to return electric power to the MCM 128 (or to the MCM 600)when subject to a braking force and where the MCM 128 is configured toconvert the received electric power to the nominal system voltageapplied to recharge the battery modules 202, 204, 206, 208, the BMS 210may adopt a “Regeneration” state 316 while the battery modules 202, 204,206, 208 are being recharged by action of the motor 130. The BMS 210returns to the Run state 312 when the motor 130 stops recharging theelectric system 312. The BMS 210 may repeatedly alternate between theRun state 312 and the Regeneration state 316 during operation of theelectric system 200. When the electric system 200 is stopped by the useror by an abnormal condition, the BMS 210 moves to the Shutdown state314, during which it may send a disconnect indication to the EVM 252 onthe system bus 254 if the stoppage or abnormal condition is firstdetected by the BMS 210, and then to the Off state 302.

Abnormal conditions may eventually be detected by various components ofthe electric system 200 or by the user while the BMS 210 is in any ofthe previously described states. An abnormal condition may be detectedby the BMS 210 or by one of the other BMSs 212, 214 or 216. If theabnormal condition is detected by the BMS 210, the BMS 210 may informthe EVM 252 via the system bus 254. The abnormal condition may also bedetected by the EVM 252, either directly or by action of the VIM 266, ofthe emergency stop switch 268 or of the hazard switch 270. The abnormalcondition may further be detected by the MCM 128, which in turn providesinformation to the EVM 252 via the driving bus 260. The BMS 210 isinformed of the abnormal condition detected by the EVM 252 or by theBMSs 212, 214 or 216 via the system bus 254. In an implementation, oneor more of the BMSs 210, 212, 214, 216 may be configured to detect anabnormal voltage and/or a temperature of the respective battery module202, 204, 206, 208, or an excessive current flowing therethrough. Use ofother sources of abnormal condition may be contemplated, including forexample sensors of the control voltage and/or sensors of the nominalsystem voltage, sensors coupled to the motor 130 for detecting atemperature of the motor 130, and the like.

A state of the BMS 210 upon detection of an abnormal condition isillustrated as “Any” state 318 on FIG. 5 . Some abnormal conditions arenot severe and only need to be recorded in a log of the BMS 210 fortroubleshooting at a later time. Possible examples of such abnormalconditions include, without limitation, a level of current flowingthrough the battery modules 202, 204, 206, 208 exceeding a first currentthreshold, or a temperature of the battery modules 202, 204, 206, 208exceeding a first temperature threshold. An abnormal condition may alsobe related to an abnormally low temperature or voltage of the batterymodules 202, 204, 206, 208. When an abnormal condition of low severityis detected, the BMS 210 moves to a “Fault” state 320 and recordsinformation about the abnormal condition. The BMS 210 then returns tothe previous state, illustrate as “Any Previous” state 322. In animplementation, the BMS 210 may send a signal via the system bus 254 tothe EVM 252 before returning to the Run state 320 so that the EVM 252 isaware of the abnormal condition. If however a detected abnormalcondition has a high severity, for example when the abnormal conditioncould lead to damage or to an unsafe operation of the electric system200, the BMS 210 moves to an “Error” state 324. Possible examples ofsuch error conditions include, without limitation, a level of currentflowing through the battery modules 202, 204, 206, 208 exceeding asecond current threshold greater than the first current threshold, or atemperature of the battery modules 202, 204, 206, 208 exceeding a secondtemperature threshold greater than the first temperature threshold. Anerror condition may also be related to an abnormally low temperature orvoltage of the battery modules 202, 204, 206, 208. The log of the BMS210 records information about the abnormal condition for troubleshootingpurposes. In an implementation, the BMS 210 may send a signal via thesystem bus 254 to the EVM 252 so that the EVM 252 is informed of theabnormal condition. The BMS 210 then moves to the Shutdown state 314followed by the Off state 302.

Details of operation in the BMS 210 in the Shutdown state 314 may varyaccording to the reasons for entering this state. Shutdown of theelectric system 200 may be initiated by the BMS 210, by the EVM 252, orby another component of the electric system 200 forwarding an errorindication to the BMS 210 or to the EVM 252. If the BMS 210 initiatesshutdown of the electric system 200, the BMS 210 provides a shutdownindication to the EVM 252. If the EVM 252 initiates shutdown of theelectric system 200, the EVM2 252 provides a shutdown indication to theBMS 210. In an implementation, a plurality of signals may be exchangedbetween the BMS 210 and the EVM 252 while the BMS 210 is in the Shutdownstate 314. The BMS 210 leaves the Shutdown state 314 when all activitiesof the battery module 202 are ready for termination and enters the Offstate 302.

FIG. 6 is a finite state diagram of an electric vehicle module (EVM). Afinite state diagram 400 shown on FIG. 6 is applicable to the EVM 252.The diagram 400 illustrates most possible state variations of the EVM252. In an implementation, the states that are illustrated in thediagram 400 are software states of the EVM 252. The followingdescription of these states will be best understood considering FIG. 2and its description.

An initial state of the EVM 252 is an “Off “state 402, when the electricsystem 200 is not operating (i.e. not turned on by the user) and whenthe charger 242 is not connected to the external power source. The EVM252 transits from the Off state 402 to an “Initialization” state 404upon wake-up of the electric system 200. The EVM 252 executes systemverification tasks while in the Initialization state 404. Any failure ofthe tasks performed by the EVM 252 while in the Initialization state 404causes the EVM 252 to move to a “Shutdown” state 412, which is describedhereinbelow. After completion of the tasks of the Shutdown state 412,the EVM 252 returns to the Off state 402.

The wake-up condition may be present when the EVM 252 receives, via thesystem bus 254, an indication that the electric system 200 is connectedto a computer or similar device (not shown), in which case the EVM 252transits from the Initialization state 404 to a “Bootloader” state 406for receiving a software update, a firmware update, or a calibrationupdate. The EVM 252 normally returns to the Off state 402 once theupdate is completed.

Alternatively the wake-up condition may be a consequence of theenergizing trigger applied to the BMS 210 and of resulting operations inthe BMS 210 and in the battery modules 202, 204, 206, 208. The EVM 252enters the Initialization state 404 when it becomes powered by thevoltage converter 256, substantially at the control voltage, shortlyafter the closing of the switched current-limiting path 286 in theinterrupter 228. The EVM 252 moves from the Initialization state 404 toa “Charging” state 408 or to a “Run” state 410 when it receivesinformation about the energizing trigger from one of the BMS 210, 212,214, 216 via the system bus 254. In an implementation, the EVM 252 waitsuntil all the BMS 210, 212, 214, 216 have reported their successfulinitialization before moving to the Charging state 408 or to the Runstate 410. The EVM 252 either moves from the Initialization state 404 tothe Charging state 408 or to the Run state 410 depending on the natureof the energizing trigger. If the energizing trigger is a continuouscharging command, indicating that the battery modules 202, 204, 206 and208 of the electric system 200 are being recharged, the EVM 252 moves tothe Charging state 408. If the energizing trigger is a transient startcommand, indicating a start of the electric system 200, the EVM 252moves to the Run state 410. In an implementation, the EVM 252 may enterthe Run state 410 when the vehicle key is rotated and locked in a“running” position of a vehicle key cylinder (not shown) to close thekey switch 274. Whether in the Charging state 408 or in the Run state410, the EVM 252 energizes the coil 258 to close the contactor 234 andthereby close the switched non-current-limiting path 288 of theinterrupter 228. The coil 258 will remain energized until shutdown ofthe electric system 200. Following closing of the switchednon-current-limiting path 288 of the interrupter 228, the EVM 252 sendsa signal to the BMS 210 via the system bus 254 to allow charging of thebattery modules 202, 204, 206, 208 or to allow running of the electricsystem 200. In response, the BMS 210 moves from its Precharge state 308to its Charging state 310 or to its Run state 312, depending on thenature of the signal received from the EVM 252.

Having entered the Charging state 408, the EVM 252 may remain in thatstate for as long as the charger 242 is connected to the external powersource and applies the energizing trigger to the BMS 210. Following adisconnection of the charger 242, as a part of the tasks executed in itsShutdown state 314, the BMS 210 forwards a disconnect indication to theEVM 252 via the system bus 254. The EVM 252 moves to a Shutdown state412, which is described hereinbelow. After completion of the tasks ofthe Shutdown state 412, the EVM 252 returns to the Off state 402.

Having entered the Run state 410 following a start of the electricsystem 200, the EVM 252 may remain in that state for as long as theelectric system 200 is not stopped by the user or by an abnormalcondition. When the electric system 200 is stopped by the user or by anabnormal condition, the EVM 252 moves to the Shutdown state 412 and thento the Off state 402. If the stoppage or abnormal condition is firstdetected by the BMS 210, the EVM 252 may enter the Shutdown state 412following receipt, on the system bus 254, of a disconnect indicationfrom the BMS 210.

Abnormal conditions may eventually be detected by various components ofthe electric system 200 or by the user while the EVM 252 is in any ofthe previously described states. Events that may lead to the detectionof an abnormal condition are described in the foregoing description ofFIG. 5 . If the abnormal condition is detected by one of the BMS 201,212, 214, 216, information about the abnormal condition is forwarded tothe EVM 252 via the system bus 254, for example in the form of adisconnect indication.

A state of the EVM 252 upon detection of an abnormal condition isillustrated as “Any” state 414 on FIG. 6 . Some abnormal conditions arenot severe and only need to be recorded in a log of the EVM 252 fortroubleshooting at a later time. When an abnormal condition of lowseverity is detected, the EVM 252 moves to a Fault state “416” andrecords information about the abnormal condition. The EVM 252 thenreturns to the previous state, illustrate as “Any Previous” state 418.Depending on a type of the abnormal condition having caused the EVM 252to move to the Fault state 416, the EVM 252 may return to the Run state410 with an alteration causing a limitation of the commands sent to theMCM 128 via the driving bus 260 in order to control a limitedperformance of the motor 130; this alteration may for example be appliedwhen a low voltage condition of the battery modules 202, 204, 206, 208is detected. If however a detected abnormal condition has a highseverity, for example when the abnormal condition could lead to damageor to an unsafe operation of the electric system 200, the EVM 252 movesto an “Error” state 420. The log of the EVM 252 records informationabout the abnormal condition for troubleshooting purposes, and thenmoves to the Shutdown state 412 followed by the Off state 402.

An “Emergency Stop” state 422 may also follow Any previous state 414when the user activates the emergency stop switch 268 to stop theelectric system 200. Likewise, removal of the vehicle key from thevehicle, causing the opening of the key switch 274, will disconnect theMCM 128 from the control voltage and this event will be detected by theEVM 252, for example by detection of a loss of signaling from the MCM128, and cause the EVM 252 to enter the Emergency Stop state 422. TheEmergency Stop state 422 is also followed by the Shutdown state 412 andby the Off state 402.

Details of operation in the EVM 252 in the Shutdown state 412 may varyaccording to the reasons for entering this state. Shutdown of theelectric system 200 may be initiated by the BMS 210, by the EVM 252, orby another component of the electric system 200 forwarding an errorindication to the BMS 210 or to the EVM 252. If the BMS 210 initiatesshutdown of the electric system 200, the BMS 210 provides a shutdownindication to the EVM 252. If the EVM 252 initiates shutdown of theelectric system 200, the EVM2 252 provides a shutdown indication to theBMS 210. In an implementation, a plurality of signals may be exchangedbetween the BMS 210 and the EVM 252 while the EVM 252 is in the Shutdownstate 412. The EVM 252 deenergizes the coil 258 and leaves the Shutdownstate 412 when activities in all components of the electric system 200are ready for termination and enters the Off state 402.

FIG. 7 is a logic diagram of a method for energizing the electric systemof FIG. 2 according to an implementation. A sequence shown in FIG. 7comprises a plurality of operations, some of which may be executed invariable order, some of the operations possibly being executedconcurrently, and some of the operations being optional.

The sequence starts at operation 500 when the energizing trigger isapplied to the first battery subassembly 282 that includes the batterymodules 202, 204 in the example of FIG. 2 . In response to theenergizing trigger, the first battery subassembly 282 is connected inseries to the second battery subassembly 284, including the batterymodules 206, 208, via the switched current-limiting path 286 of theinterrupter 228, at operation 502. The nominal system voltage providedby the first and second battery subassemblies 282, 284 may be convertedto the control voltage at operation 504 by the voltage converter 256.The system controller, for example the EVM 252, is energized atoperation 506, possibly at the control voltage. The first and secondbattery subassemblies 282, 284 are then connected in series via theswitched non-current-limiting path 288 of the interrupter 228 atoperation 510. This operation 510 may either immediately followoperation 506, or may follow operation 508, which includes the electricsystem 200 waiting for at least one of the following conditions: aminimum time delay having passed after connecting the first and secondbattery subassemblies 282, 284 via the switched current-limiting path286, the electric system 200 verifying that a minimum combined voltageis provided by the first and second battery subassemblies 282, 284, orthe electric system 200 verifying that a current flowing through thefirst and second battery subassemblies 282, 284 is less than a maximumvalue. In an implementation, the verifications of operation 508 areperformed by one or more of the BMSs 210, 212, 214, 216.

Following the connection of the first and second battery subassemblies282, 284 via the switched non-current-limiting path 288 at operation510, the switched current-limiting path 286 between the first and secondbattery subassemblies 282, 284 is disconnected at operation 512.Operation 514 considers whether the energizing trigger applied atoperation 500 is a start command or a charging command. If theenergizing trigger is a start command, a start indication is forwardedto the system controller at operation 516. A motor controller, forexample the MCM 128, is energized with the control voltage at operation518. Delivering electric power from the motor controller to the motor130 at the nominal voltage follows at operation 520. If the energizingtrigger is a charging command, a charging indication is forward to thesystem controller at operation 522. The first and second batterysubassemblies 282, 284 are charged at operation 524. The electric system200 may then remain in it current state until shutdown.

Modifications and improvements to the above-described implementations ofthe present technology may become apparent to those skilled in the art.The foregoing description is intended to be exemplary rather thanlimiting.

What is claimed is:
 1. An electric system, comprising: a batteryassembly; a current limiter; a non-current-limiting path in parallelwith the current limiter; a first battery management system (BMS)adapted for causing the battery assembly to energize the electric systemusing the current limiter upon a start of a precharge phase; and anelectric vehicle module (EVM) communicatively coupled to the BMS, theEVM being adapted for causing the battery assembly to energize theelectric system using the non-current-limiting path following acompletion of the precharge phase.
 2. The electric system of claim 1,wherein: the current limiter comprises a first contactor; thenon-current-limiting path comprises a second contactor; the first BMS isfurther adapted for causing the battery assembly to energize theelectric system using the current limiter by causing closing of thefirst contactor; and the EVM is further adapted for causing the batteryassembly to energize the electric system using the non-current-limitingpath by causing closing of the second contactor.
 3. The electric systemof claim 1, further comprising a system bus communicatively coupling theEVM to the BMS.
 4. A method for energizing an electric system,comprising: applying an energizing trigger to a first controller of theelectric system; in response to the energizing trigger causing, by thefirst controller, energizing of the electric system from acurrent-limited battery source during a precharge phase; followingcompletion of the precharge phase forwarding, from the first controllerto a second controller, an indication of the energizing trigger; and inresponse to receiving the indication of the energizing trigger causing,by the second controller, energizing of the electric system from anon-current-limited battery source.
 5. The method of claim 4, furthercomprising: closing a first contactor connecting the current-limitedbattery source to the electric system to cause energizing of theelectric system from the current-limited battery source; and closing asecond contactor connecting the non-current-limited battery source tothe electric system to cause energizing of the electric system from thenon-current-limited battery source.
 6. The method of claim 4, whereinthe indication of the energizing trigger is forwarded on a system buscommunicatively coupling the first controller and the second controller.7. An electric system comprising: a first battery module comprising atleast one first battery cell, a first battery management system (BMS)and a first BMS switching power supply, the at least one first batterycell and the first BMS switching power supply being disconnected whenthe first BMS is in an inactive state, the at least one first batterycell and the first BMS switching power supply being connected when thefirst BMS is in a powered state; a second battery module electricallyconnectable to the first battery module, the second battery modulecomprising at least one second battery cell, a second BMS and a secondBMS switching power supply, the at least one second battery cell and thesecond BMS switching power supply being disconnected when the second BMSis in an inactive state, the at least one second battery cell and thesecond BMS switching power supply being connected when the second BMS isin a powered state; and a user-controlled switch adapted for causing aconnection of the at least one first battery cell to the first BMSswitching power supply for energizing the first BMS and for changing thefirst BMS from the inactive state to the powered state; the first BMSbeing adapted for causing a connection of the at least one secondbattery cell to the second BMS switching power supply for energizing thesecond BMS and for changing the second BMS from the inactive state tothe powered state when the first BMS is in the powered state; the firstBMS being further adapted for closing a current-limiting path placed inseries between the first and second battery modules to start a prechargephase of the electric system once a communication between the first BMSand the second BMS is established.
 8. The electric system of claim 7,wherein the first BMS is further adapted for performing initialverifications before closing the current-limiting path.
 9. The electricsystem of claim 8, wherein the initial verifications comprise aconfirmation of the communication between the first BMS and the secondBMS.